The present invention relates to locomotive fuel conservation, and more particularly to automatically starting and stopping locomotive engines for the purpose of conserving fuel.
In recent years, locomotives have been equipped with systems for automatically starting and stopping their engines when one or more conditions exist. The primary purpose of such systems is to conserve fuel, thereby lowering fuel costs while also preserving precious energy resources. For instance, a locomotive may be configured to automatically shutdown after operating for a certain amount of time in a parked idle state to prevent the locomotive from needlessly wasting fuel. The locomotive may then automatically restart when, for example, an operator signals an intention to motor the locomotive, such as by moving a direction controller (known as a reverser) from a center position (that is, from a xe2x80x9cneutralxe2x80x9d position). A locomotive may also be configured to automatically restart a certain amount of time following an automatic shutdown, such as two or four hours, or when other conditions exist.
The automatic engine start and stop (AESS) system described above has been implemented not only in locomotives which operate independently, but also in multiple locomotives that operate together (i.e., in consist) for providing cumulative (or reserve) towing capacity. The front locomotive in the consist is usually designated the lead unit while the other locomotives are designated trail units. Each trail unit typically receives a trainline signal representing the position of the lead unit""s reverser, and treats that signal as representing the position of its own reverser (which is typically placed in the center position when configuring the locomotive for trail unit operation). In the case where a locomotive""s reverser must be in the center position to enable the AESS system, placing the lead unit""s reverser in the center position will allow the AESS system to be enabled in each locomotive in the consist. Similarly, in the case where moving an automatically shutdown locomotive""s reverser from the center position induces an automatic engine restart, moving the reverser in an automatically shutdown lead unit from the center position induces an automatic restart for each automatically shutdown locomotive in the consist.
Although deployed AESS systems have proven reliable, the inventors hereof have discovered human factors that result in unrealized fuel savings. For example, they discovered that operators frequently take steps to prevent automatic engine shutdowns. This is apparently done so that lead units (including single units operating independently and not in a consist) remain available upon demand (i.e., for operator peace of mind), and to provide climate control (i.e., heating and air conditioning) to the operator cabin. Common approaches to preventing automatic engine shutdowns include maintaining a lead unit""s reverser out of the center position, and manually moving an automatic start/stop disable switch (ASDS), typically located in a CA1 locker, to an xe2x80x9coffxe2x80x9d position. Service personnel may also forget to move the ASDS to its xe2x80x9conxe2x80x9d position after switching it xe2x80x9coffxe2x80x9d for safety during maintenance procedures. Regardless of how or why it occurs, preventing an AESS system in a single locomotive from performing its intended function obviously results in lost fuel savings. Moreover, preventing an auto shutdown in the lead unit of a consist may prevent an auto shutdown for each trail unit in the consist. Thus, although an operator may, for example, maintain the lead unit""s reverser out of the center position for the sole purpose of keeping the lead unit running, the net result may be that two, three, or even more trail units remain running and consuming fuel, in addition to the lead unit.
A related problem discovered by the inventors is unnecessary operator induced restarts, which occur, for example, when an operator moves the reverser of an automatically shutdown locomotive away from the center position. The apparent reasons for such restarts are essentially the same as those for preventing automatic engine shutdowns, namely, to resume on-demand availability of lead units and to provide climate control to the operator cabin. Again, while an operator""s intention may be to simply restart a lead unit, the effect may be to restart every locomotive in a consist.
The inventors have determined that unrealized fuel savings are often an order of magnitude greater than actual fuel savings primarily due to operator interaction issues, and have therefore recognized a need for AESS systems that can interact more favorably with locomotive operators, taking into account operator needs and concerns, so as to realize increased fuel savings and conservation.
In order to solve these and other needs in the art, the inventors hereof have designed an automatic engine start/stop (AESS) system for locomotives which takes into account operator needs and concerns by enabling operators to locally prevent automatic shutdowns of their locomotives without disabling their AESS systems. Thus, operators can maintain their lead (and/or other) units running (i.e., for peace of mind, climate control, etc.) without disabling their AESS systems and without prohibiting other locomotives in consist from automatically shutting down. The system preferably includes an inhibit switch located in each locomotive control cabin which, when actuated by an operator, prevents that locomotive (and only that locomotive) from automatically shutting down within a predefined duration of time, such as two hours. In the event the operator subsequently motors the locomotive before the predefined duration of time expires, the AESS system is preferably reset. Otherwise, when the predefined duration of time has passed, the locomotive will automatically shutdown (assuming a set of automatic engine shutdown parameters are satisfied at that time). The present invention also provides several techniques for reminding and prompting an operator to enable an AESS system, including sounding an alarm, displaying and recording fault data, and inhibiting motoring of the locomotive when the AESS system is disabled and the operator calls for braking or motoring capability.
According to one aspect of the present invention, an engine control system for a locomotive includes a memory device for storing computer instructions, a computer processor for executing the computer instructions stored in the memory device, the computer instructions configuring the computer processor to output one or more commands when one or more predefined conditions exist, and engine control hardware for controlling the locomotive engine in response to commands output by the computer processor. The computer processor includes an input for receiving a signal indicative of whether an automatic engine stop system is enabled. The computer instructions configure the computer processor to normally output an engine shutdown command when the automatic engine stop system is enabled and a set of automatic engine shutdown parameters are satisfied. The computer processor also includes an input for receiving an inhibit command from an operator of the locomotive. The computer instructions further configure the computer processor to at least delay outputting the engine shutdown command in response to the inhibit command.
According to another aspect of the present invention, a method of implementing an automatic engine stop system in a locomotive includes deactivating the automatic engine stop system in response to operator input to prevent the automatic engine stop system from automatically shutting down the locomotive without disabling the automatic engine stop system.
According to yet another aspect of the invention, a method for prompting an operator of a locomotive to enable an automatic engine stop system includes sounding an audible alarm when the automatic engine stop system is disabled and the operator initiates braking or motoring.
According to a further aspect of the invention, a method for prompting an operator of a locomotive to enable an automatic engine stop system includes inhibiting motoring of the locomotive until the automatic engine stop system is enabled.
According to still another aspect of the invention, a computer-readable medium has computer-executable instructions recorded thereon for implementing any one or more of the systems and methods described herein.
Other aspects and features of the present invention will be in part apparent and in part pointed out hereinafter.